An inflatable vehicle occupant protection device, such as an air bag, is inflated upon the occurrence of a vehicle collision. The air bag is part of an apparatus which further includes a collision sensor and an inflator. The collision sensor senses vehicle conditions that indicate the occurrence of a collision. When the collision sensor senses a collision-indicating condition of at least a predetermined threshold level, the inflator is actuated. The inflator then emits inflation fluid which inflates the air bag into the vehicle occupant compartment to help protect an occupant of the vehicle from forcefully striking parts of the vehicle as a result of the collision.
An air bag and an inflator are typically assembled together as parts of an air bag module. The air bag module is located in the vehicle adjacent to the vehicle occupant compartment. For example, a passenger side air bag module is typically located in the vehicle instrument panel. A driver's side air bag module is typically located on the vehicle steering wheel. In addition to the air bag and the inflator, a driver's side air bag module typically includes a retainer and a cover. The retainer secures the air bag and the inflator together. The cover conceals airbag and inflator from the vehicle occupant compartment, and includes at least one deployment door which extends over the air bag.
When inflation fluid emitted from the inflator begins to inflate the air bag, it moves the air bag outward against the deployment door. The deployment door is ruptured by the force of the fluid pressure in the air bag, and is moved out of the path of the air bag as the inflation fluid continues to inflate the air bag outward into the vehicle occupant compartment. This inflation generates a force which requires the module to be mounted to the vehicle securely.